The administrative county of Merioneth, created under the Local Government Act 1888, was abolished under the Local Government Act 1972 on April 1, 1974. The bulk formed the Meirionnydd district in the new county of Gwynedd, with a small protusion in the north-east (the Edeyrnion Rural District) becoming part of the Glyndŵr district of Clwyd. Since Local Government (Wales) Act 1994 came into force in 1996 the Glyndŵr part now forms part of the principal area of Denbighshire, with the rest remaining in Gwynedd.
Merionethshire is a maritime county, bounded to the north by Caernarfonshire, to the east by Denbighshire, to the south by Montgomeryshire and Cardiganshire, and to the west by Cardigan Bay. Its total area is 1,731 km², and it is one of the more sparsely populated counties of the UK. It is also one of the strongest Welsh-speaking parts of Wales. The coastline consists alternately of cliffs and stretches of sand and the area generally is the most mountainous in Wales; a large part of the Snowdonia National Park lies within it. The greatest heights are Aran Fawddwy 905 m (2970 ft) and Cadair Idris 893 m (2929 ft). The chief rivers are the Dwyryd, the Mawddach and the Dyfi. Waterfalls and small lakes are numerous, the largest being Bala Lake (4 miles long and broad).
Merioneth was an important part of the Welsh slate industry in the nineteenth and twentieth centuries, with major quarrying centres at Blaenau Ffestiniog in the north of the county and Corris in the south.
The main towns are
The main industries today are agriculture, forestry and tourism.